The Applicant has developed a range of Memjet® inkjet printers as described in, for example, WO2011/143700, WO2011/143699 and WO2009/089567, the contents of which are herein incorporated by reference. Memjet® printers employ one or more stationary inkjet printheads in combination with a feed mechanism which feeds print media past the printhead in a single pass. Memjet® printers therefore provide much higher printing speeds than conventional scanning inkjet printers.
Currently, multi-color Memjet® printheads for desktop printing are based on a liquid crystal polymer (LCP) manifold described in U.S. Pat. No. 7,347,534, which delivers four colors of ink through five color channels (CMYKK) of the printhead to a plurality of butted printhead chips. The Memjet® printhead chips are bonded to a surface of the LCP manifold via an apertured die-attach film comprised of a central polymer web sandwiched between opposite adhesive layers. The LCP manifold cooperates with the die-attach film to direct ink from each of five ink channels to respective color planes of each printhead chip via a series of tortuous ink pathways. Redundancy in the black (K) channel is useful for improving print quality and black optical density.
However, at high print speeds, the LCP manifold has some practical limitations. The multiple labyrinthine ink pathways for delivering multiple inks from the LCP manifold to the printhead chips may be responsible for unexpected de-priming when the printhead is running at high speeds. Without a sufficiently large body of ink close to the printhead chips, the chips may become starved of ink under periods of high ink demand and lead to chip de-priming. Secondly, the labyrinthine ink pathways are susceptible to trapping air bubbles; if an air bubble becomes trapped in the system, the printhead chips will become starved of ink and de-prime. It would therefore be desirable to provide a color printhead suitable for high-speed printing, which is tolerant of air bubbles and less susceptible to de-prime events.
Whilst LCP is a satisfactory choice of material for A4 printheads, having a CTE similar to silicon, it typically lacks the required rigidity to manufacture longer printheads (e.g. A3 printheads). It would be desirable to provide a printhead architecture suitable for manufacturing printheads that may be longer than A4-sized.
Printhead electrical connections in pagewide printheads are typically via one or more flex PCBs, which wrap around an exterior sidewall of the printhead. An alternative, more complex approach is to route electrical wiring through layers of a laminated ceramic ink manifold (see, for example, U.S. Pat. No. 6,322,206 assigned to HP, Inc.). However, flex PCBs are expensive and add significantly to manufacturing costs. Moreover, bending of a flex PCB through a tight angle places strain on the PCB and limits the components that may be incorporated thereon. It would therefore be desirable to provide a robust, inexpensive alternative to conventional electrical wiring arrangements used in pagewide printheads.
For inkjet digital presses, multiple monochrome printheads are typically stacked along a media feed direction, as described in U.S. Pat. No. 8,845,080. This arrangement enables very high speed printing by making use of multiple ink channels in each printhead to print one color of ink. However, a problem with stacking printheads in this manner is that precise registration of the printheads is required when printheads are replaced by the user. Further, there are high demands on media feed mechanisms, which must maintain alignment of the print media with the printheads through a relatively long print zone. It would therefore be desirable to provide a replaceable printhead suitable for desktop printing, which can print multiple colors at high speeds and does not require registration of multiple printheads in the field.